I had to learn Morse code when I trained to be a ships radio officer. I remember it was a long slog but I've never forgotten it, never been of much use to me though....
Start off by learning the alphabet, opposites (N, A) is a good idea. Learn every letter at the start. Identify your "weak" letters and practice harder on those or you'll have trouble with them later on. Prcatice by trying to decode newspaper headlines or people's names (don't go up to them and say "Did you know your name is dah di dah dah etc etc", you'll lose all your friends). Get or write a PC program to practice receiving . Start slowly, as slow as a couple of words per minute. Don't be tempted to speed up until you have perfected your current speed. If you speed up too early you can make habitual errors that are very hard to shake off (like continually transposing L and F for instance).
I wouldn't recommend using tapes as you find you learn the tapes not the code, although they are better than nothing of course.
Good luck.